Transfer sheet



Patented June 26, 1951 UNITED STATES PATENT OFFICE TRANSFER SHEET Vilemina Groak, London, England, assignor to .Lamson Paragon :Supply Company Limited,

London, England, .a British company .ApplicationOctober10, 1946, Serial No.702,361 In Great Britain October 29,1945

"original work isexe'cuted. The invention is pri- "marily %though not exclusively directed to the productionof stationery bearing transfer copying material on the backs of the sheets or strips.

"Transfer copying stationery, frequently termed carbonized stationery, as "hitherto produced has necessitatedthe use-of a heavy paper to counteract penetration and showing through to the front ofthe coloured transfer materialapplied to the back. Thisconstitutes -a serious-drawback since apart from the higher cost of heavy or thick paper as compared with thin, a limitation is imposed uponthe number of copies which can be produced using 'multi-layer stationery, due to lackof legibility'in the lower layers, and about eight copies has come to be regarded as the maximum which canbe produced.

The common alternative has been to employ "thin uncarbonized stationery interleaved with ordinary thin carbon paper but whilst the results may be satisfactory from the-point of view of legibility, this method is expensive and involves much less of time'and furthermore it does not permit selective duplicating on different areas of the various sheets forming a set.

The production of carbonized stationery as hitherto known has also been 'a difficult operation in itself involving the use of heavy, nondrying transfer inks which are difficult to apply and prone tosmudging, unless special plant is employed ffortheirapplicationto the paper.

It i's'amongsttheiobjects of the present invention to provide a method for the easy preparationofpaper-or like sheets crstrips coated with transfer copying materials, which exhibit .little orno colour-penetration to the front-of even thin paper, e..g. a sulphite cellulosepaper having a weight of 30--.3V5 .grams per square meter, the transfer composition having a hard and nonsmudgy surface, andre'tainingits transfer copying properties'for a long period of time.

The invention is illustrated in the accompanying'diagrammatic drawing in which Fig. lshowsone form of transfer-copyingsta- *tioneryproducedin-accordance with the invention,

Fig. '2 is an enlargedtransverse sectional View of the-"stationeryshown-in-Figure 1,- and 2 Fig. 3 is a further enlarged transverse sectional view vof the stationery shown in Fig. v1,

illustrating, "diagrammatically, the :mode of operation thereof.

Referring to the drawing,'the presentinvention comprises transfer copying stationery, e. g. in

sheet or strip "form, comprisingmaterial :I .hav-

ing a set and opaque firstlayer 2 applied to the whole or to selected parts :of the surface 13 of the material I, said .first layer being pressuresensitive and substantially impervious to printing ink and being formed by applying to thesurface 3 of 'the material fl a setting but non-drying composition or a setting composition including a large proportion :of oneor more non-drying components and allowing the applied composition toset to form said first :layer :2. The transfer copyin stationery also includesxa second layer 4 formed by applying a printing ink comprising either a'pigmented ink, a dye-solution ink or aimixture thereof to'the whole or a part of the surfaceTS of thefirst layer I and per.-

mittingtheapplied'ink .to dry to form a dry and coherent :filmadhering as va second layer 4 to the surface 5 of the first'layer l.

'Bythe expression non-drying is to be understood compositions .or components which after setting do not oxidise or polymerise or change their nature by anysubstantial evaporation or absorption. A setting but non-drying composition is a composition iwhich,'th0ugh readily softened or melted at temperatures above about'50 C. will set at room temperature to'form a more or less solid film havin pressure-sensitive properties. The word non-drying is used to distinguish from compositions which dry by evaporation, or oxidise, polymerise or otherwise change their nature chemically, to form dry and coherent films whichare not'to any useful extent pressure-sensitive. Thus'one may contrast ordinary printing ink which dries to forma coherent filmhavin in itself, no appreciable tendency to transfer (i. e. a film which is not pressure-sensitive), with a composition such as is given as an example later in this-specification, which after hot application to a paper sheet-will set (but not *dry) to form a pressure-sensitive carrier layer on the paper.

The second applied ink'layer adheresfirmly to the surface of the carrier without impregnation 'thereofand is capable of being transferred when the-pressure is applied. I

The finished material may be inthe form'of reeled or folded strip or cut sheets.

'The thickness 'of the first or carrier layer is are thus caused to adhere thereto.

about the same as, or even slightly less than, that of the coating or an ordinary one-time carbon paper but varies with the type of paper of other web used. For instance a paper with a glossy surface will require a thinner carrier layer than a paper having a matt surface.

Ordinary known coloured dye solution inks or pigmented inks or mixtures of both are used for the second layer, and such inks as dry rapidly by evaporation are the most suitable. They are applied after the impervious carrier layer has been allowed to set, and thus is formed a film of coloured material capable of being transferred by pressure and having a firm and non-smudging surface and which also serves as a protective coating for the non-drying pressure-sensitive carrier layer whereby the properties thereof necessary for transfer copying are preserved for a very long period of time. The use of the opaque carrier layer impermeable to the applied coloured layer ensures that little or no colour effect from the coloured layer can be observed from the front of even very thin paper so treated, so that legibility of the writing, drawing, typing, printing or other form of inscription both in the original and the copies is ensured.

The second layer, which is allowed to dry in any suitable manner depending upon the particular kind of printing ink used, forms a thin dry, coherent film on the surface of the first and pressure-sensitive layer. Parts of this dry and coherent film are capable of being transferred to a copy sheet, by pressure applied to the back (i. e. the uncoated surface) of the stationery, together with corresponding thin films or small portions of the pressure-sensitive carrier layer. Thus, transfer of the dry second layer is dependent upon the pressure-sensitive properties of the first (i. e. carrier) layer.

vIt will be understood that whilst parts of the dry printing ink constituting the second layer are transferred to the copy sheet with corresponding very thin films'of the pressure-sensitive layer the colour of the transferred material is not to any noticeable extent obscured by the slight amount of pressure-sensitive composition transferred with it since the latter, by virtue of its pressure-sensitive property, tends to become squeezed around the edges of the transfered'portio'ns of the colored second layer and carrier) layer is opaque in the bulk (i. e. it can form an opaque layer), but is practically transparent compared with the capacity of the drying inks used for the second layer, when viewed in very thin films.

The portions of printing ink transferred to the copy sheet from the second layer are pressed slightly into the surface of the copy sheet and It is also considered probable that the slight amount of pressure-sensitive composition which, as outlined above, tends to be squeezed around the edges of the transferred portions of the printing ink and to a certain extent mixed therewith,

also facilitates adherence of the latter to the 4 matically in Fig. 3 of the drawing. As a result of pressure applied to the uncoated surface 6 of the paper I, portions 1 of the second layer of ordinary dry printing ink, 4, are transferred to the receiving surface 8 of the copy sheet 9. The surface 8 is normally in contact with the surface of the second layer 4 but in the drawin it is shown spaced therefrom for the sake of clarity. In addition to the portions 1 of the second layer 4, very thin films of the first layer 3 become detached, as shown at I0, and transferred with the portions 1 of the second layer 4, probably helping the portions 1 of dry printing ink to adhere to the copy paper 8 but without obscurin the latter to any noticeable extent.

The composition for the carrier layer is rendered opaque by the inclusion of a filler or pigment or other suitable compounds, the filler being white or lightly coloured, or the composition may be otherwise lightly tinted to match the colour of the stationery, and compositions are contemplated in accordance with the invention some of which are suitable for hotand others for cold application.

The carrier layer composition may be applied over the whole or selected parts only of the paper or other web e. g. it may be in patches or conform to desired configurations according to specific requirements and the sheets may be provided in known manner with out out portions, apertures for sheet or web feed and like purposes.

Application of the carrier layer to the paper or other web may be effected with the aid of a coating machine such as is used for the production of ordinary carbon paper or by means of printing machines provided if necessary with a heated inking unit or a heated printing unit or both, or by spraying or brushing.

The followin is a specific example of a compo: sition suitable for hot application in the production of the opaque pressure-sensitive carrier layer.

Sixteen parts by weight of antimony oxideand five parts of titanium dioxide, together with a mixture of fifteen parts of petroleum jelly, ten parts of a light coloured mineral oil of medium viscosity and twenty parts of liquid paraffin, are treated in a printing ink roller mill until the pigments are well ground as in the case of printing ink preparation. Ten parts of prime yellow carnauba wax, ten parts of prime candelilla wax, twelve parts of white beeswax, three parts of a polythene plastic known as Mycropar A (a wax-like substance with a melting point of about centigrade) and nine parts of stearin are heated over steam and melted while stirring gently and the white pigment plus oil mixture prepared as above is added slowly, stirring being continued. The final mixture is ground for about one hour preferably in a roller mill with alternate hot and cooled rollers.

Any transferable composition may however be used for the pressure-sensitive opaque carrier layer, applied in hot or cold state including those which consist of two phases, e. g. a spongy nontransferable continuous phase and a non-continuous pressure-sensitive phase which when applied fills out the pores of the spon y phase.

A normal] coating with this composition will involve an application of from 10 to 15 grams per square metre of carrier layer to be formed.

An example of a composition suitable'for cold application in the production of the opaquepressure-sensitive layer, using coating machines or an ordinary letter-press method is as follows:

Six parts by weight of zinc stearate and fourteen parts of antimony oxide are ground together with fifteen parts of. petroleum. jelly and twenty parts of liquid paraffin. Six parts of prime yellow carnauba wax, six parts of prime candelilla wax, nine parts of white beeswax, ten parts of stearin and six parts of Russian tallow are: heated over steam until molten. The prepared white pigment mixture is added while the molten waxes are stirred and the whole. composition ground in a roller mill of the. kind used in printing ink grinding. Four passes of the material through the grinding mill are usually sufilcient. Eight parts of. xylol are added prior to the. last pass in. the grinding mill. Sixty parts of this preparation, together with forty parts of a long printing: varnish composition itself consisting of eighty parts. of a long offset varnish, six parts of zinc stearate. and fourteen parts: of antimony oxide, are ground in a coldv grinding. millto form the composition for the pressure-sensitive layer. Small additions of xylol may be made if necessary, to soften the composition during the printin or other process of application. The sub-- stance wax, Mycropar A, stearin and Russian tallow are setting but non-drying substances, and petroleum jelly, which isa non-drying substance, also tends to set under cool conditions to form a more or less, solid film.

Liquid paraffin and. zinc stearate are likewise non-drying but taken individually they are respectively a. liquid and a solid, usually powder; at." room temperature and would not normally be termed setting. In combination they can form gels, as is well. known in the art, which can be said to set, and all the substances mentioned above can be combined in suitable proportions to yield setting but non-drying compositions suitable for applying; to material such as paper sheet or stripto forma first and pressure-sensitive layer thereon.

Mycropar A is a blend, of ethyl cellulose with either a fatty acid, or wax, or both a. fatty acid and wax. It has a melting point of about 108 6. and its. appearance and behaviour are; like those of a hard wax.

The application of the. coloured; second layer to the opaque carrier layer may take place immediately following the first stage operation, subject to. the necessity of giving the opaque layer time to set and. become: relatively hard to the touch to avoid penetration or mingling of the two. layers, or such application may be effected subsequently and. even a very long time afterwards, and the coloured layer will usually though not invariably, cover the whole or a part or parts only of the surface of. the stationery according as the opaque carrier layer covers the whole or part only. On the other hand limited areas of the coloured, layers may be applied to (ielfresins or gums). and more oil or. plasticiser than the: hard-drying inks. Bhotograv-ure inks and; aniline. printing. inks. have as a vehicle; quickly evaporating solvents and serve admirably for the. present purpose- For letter-press there are available. the so.--called- "heat-set inks, which also dry by evaporation and these are the. inks which are. preferable. All such printing inks contain film-forming substances such as. e. g. cellulose. ethers and resins, which after evaporation. of: the solvent vehicle will form a. thin coloured film, which isv dry and hard to the touch. Heat-set inks may be used: but. without the assistance of heat to hasten to evaporation. of the; solvent. Should. it be necessary to employ heat, as would be of advantage on fast running machines to avoid set-off, care should be taken not to lead the. stationery over heated; rollers. The coloured layer may be exposed for a short period only, to a moderately raised temperature e. g. by running the web past a source of infra.- red radiation with, the. coloured layer facing the radiation source and taking carev that. the. carrier layer is not softened, thereby ensuring preservation of the two distinct layers. The" finishing step of applying the col-- oured ink coating material may be carried. out with the same machine as that used for application of the carrier layer or in a simple and efiicient manner utilising known printing. methods with known printing, coating or duplicating machines. or by the. use of a spray or brush.

Inv many and possibly most cases, paper or like sheet material provided with the firstcoat ing of pressure-sensitive material will be supplied to a printer for the application of the. colo ured' layer: and"v by the fact that for the: said second layer application special carbon inks: need not be used, the difiiculties. which arise: from the peculiar properties of those inks, such: a penetration of thin paper with subsequent discolorar tion at: the. front, excessive smudging, unless special processes. and/or machines are used, and difiicultofeeding of the ink to the rollers; are avoided;

A drawback in the production of carbonized stationery as hitherto known is. that the; methods of preparation thereof have been confined to letterpress printing, photogravure, coating and brushing processes and spraying but by the present invention such limitation is avoided and other processes such as lithography, offset, aniline: printing process, silkscreen. and the; wide available variety of duplicating processes may be. employed;

The. coloured: second. layer need only be very thin since it is to be completely transferred to the copy sheet by the pressure of writing, typing or printing and even faint colouration will produce. a. satisfactory result. Measured by the depth of a. layer printed in photogravure the medium. dark tone. achieved by this process is a good guidance-..

The common printing practice. of printing both front and. back of the stationary simultaneously by turning, for example on a flat-bed machine, may bev made use of in the production of stationery according to this invention by having'the dual coating; of transfer material covering: alternate halves or other sections of. the front and: back. surface of. the stationery to: be printed.

Different colours for the ultimate transfer copying stationery may be easily achieved e. g. by the common practice of splitting the ink duct 'and'runningdifferent colours side by side, 'a factor which will be of advantage where colour distinction is required in various accounting systems.

Instead of printing full surfaces or solid patches in colour, configurations and pictures in single colour or in multi-colours may be printed and made transferable by pressure. This includes half-tone efiects and minute impressions known in the art of printing as Guilloche. The latter case is of great utility in the prevention and detection of forgeries. The impression of the Writing, typing or printing instruments transfers some complete coloured top parts together with the whole or a part of the corresponding opaque carrier layer portions, from the back of the stationery to the front of the underlying sheet leaving a white or other negative of the impression on the back, thus enabling the two surfaces to be compared.

Inthe application of the colour layer to the pre-coated or first stage treated stationery by printing methods, care should be taken that the coatedside is not scratched by the dust-removing brushes commonly used in for example rtary printing machines and any serrated idler rollers should either be substituted by smooth rollers or their surfaces covered with paper or other appropriate material to render them smooth.

When the second stage operation is carried out by a letterpress process soft printing plates such as rubber stereos should be employed especially for the printing of the front of the treated stationery.

Where duplicating machines are to be used the stencil sheet is appropriately cut out and printing effected using little ink. Apparatus of the spirit type duplicating kind may also be employed, in which case a piece of the hectographic carbon corresponding in size with the area to be printed is cut and stuck to the master sheet.

It is found that the separately applied colour layer, when dry forms a sealing film over the opaque carrier layer affording protection to the latter both against deterioration of its pressure sensitivity due to atmospheric effects over long periods of time, and against smudging or other injury due to handling.

As a further agency in the detection of forgeries, chemical substances may be added to the material to be applied and more usually to the composition for the opaque carrier layer and as examples of suitable additions may be mentioned diphenylguanadene, naphthidene, pyrogalloldimethylether and diphenol as being particularly suitable.

I claim:

1. Transfer copying stationary comprising material having a set and opaque first layer, which is pressure-sensitive and substantially impervious to printing ink, and is formed by applying a setting, but non-drying, composition to at least part of a surface of said material, and a second layer consisting of a printing ink in the form of a dry and coherent film adhering to at least part of the surface of the first and pressure-sensitive layer.

' 2. Transfer copying stationery comprising material having a set and opaque first layer which is pressure-sensitive and substantially impervi- 8 ous to printing ink and is formed by applying a setting, but non-drying, composition to a surface of said material, and a second layer consisting of a pigmented printing ink in the form of a dry and coherent film adhering to the surface of the first and pressure-sensitive layer.

3. Transfer copying stationary comprising material having a set and opaque first layer which is pressure-sensitive and substantially impervious to printin ink and is formed by applying a setting, but non-drying, composition to a surface of said material, and a second layer consisting of a dye-solution printing ink in the form of a dry and coherent film adhering to the surface of the first and pressure-sensitive layer.

4. Transfer copying stationery comprising material having a set and opaque first layer which is pressure-sensitive and substantially impervious to printing ink and is formed by applying a setting, but non-drying, composition to a surface of said material, and a second layer consisting of a printing ink constituted by a mixture of a pigmented ink and dye-solution ink, said layer of printing ink being in the form of a dry and coherent film adhering to the surface of the first and pressure-sensitive layer.

5. Transfer copying stationery comprising material having a set and opaque first layer which is pressure-sensitive and substantially impervious to printing ink and is formed by applying a setting but non-drying composition to a surface of said material, said non-drying composition including an opaque filler material of a color to match the color of the composition to that of the material to which it is applied, and a second layer consisting of a printing ink in the form of a dry and coherent film adhering to the surface of the first and pressure-sensitive layer.

6. Transfer copying stationery comprising material having a set and opaque first layer which is pressure-sensitive and substantially imperviious to printing ink and is formed by applying to a surface of said material a setting but nondrying composition which includes an opaque filler material and a separate tinting medium to match the color of the composition to that of the surface of the material to which it is applied, and. a second layer consisting of a printing ink in the form of a dry and coherent film adhering to the surface of the first and pressuresensitive layer.

7. Transfer copying stationery comprising material having a set and opaque first layer which is pressure-sensitive and substantially impervious to printing ink applied to a surface of said material, and a second layer consisting of a soft-drying printing ink in the form of a dry and coherent film adhering to the surface of the first and pressure-sensitive layer.

VILEMINA GROAK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

